diff --git a/openapi_core/schema/media_types/models.py b/openapi_core/schema/media_types/models.py
index 7c53945..61b2e3d 100644
--- a/openapi_core/schema/media_types/models.py
+++ b/openapi_core/schema/media_types/models.py
@@ -32,22 +32,25 @@ class MediaType(object):
         deserializer = self.get_dererializer()
         return deserializer(value)
 
-    def unmarshal(self, value, custom_formatters=None):
+    def cast(self, value):
         if not self.schema:
             return value
 
         try:
-            deserialized = self.deserialize(value)
+            return self.deserialize(value)
         except ValueError as exc:
             raise InvalidMediaTypeValue(exc)
 
+    def unmarshal(self, value, custom_formatters=None, resolver=None):
+        if not self.schema:
+            return value
+
         try:
-            unmarshalled = self.schema.unmarshal(deserialized, custom_formatters=custom_formatters)
+            self.schema.validate(value, resolver=resolver)
         except OpenAPISchemaError as exc:
             raise InvalidMediaTypeValue(exc)
 
         try:
-            return self.schema.validate(
-                unmarshalled, custom_formatters=custom_formatters)
+            return self.schema.unmarshal(value, custom_formatters=custom_formatters)
         except OpenAPISchemaError as exc:
             raise InvalidMediaTypeValue(exc)
diff --git a/openapi_core/schema/parameters/models.py b/openapi_core/schema/parameters/models.py
index 0565f66..612b062 100644
--- a/openapi_core/schema/parameters/models.py
+++ b/openapi_core/schema/parameters/models.py
@@ -72,7 +72,7 @@ class Parameter(object):
         deserializer = self.get_dererializer()
         return deserializer(value)
 
-    def get_value(self, request):
+    def get_raw_value(self, request):
         location = request.parameters[self.location.value]
 
         if self.name not in location:
@@ -89,7 +89,7 @@ class Parameter(object):
 
         return location[self.name]
 
-    def unmarshal(self, value, custom_formatters=None):
+    def cast(self, value):
         if self.deprecated:
             warnings.warn(
                 "{0} parameter is deprecated".format(self.name),
@@ -109,21 +109,24 @@ class Parameter(object):
             raise InvalidParameterValue(self.name, exc)
 
         try:
-            casted = self.schema.cast(deserialized)
+            return self.schema.cast(deserialized)
+        except OpenAPISchemaError as exc:
+            raise InvalidParameterValue(self.name, exc)
+
+    def unmarshal(self, value, custom_formatters=None, resolver=None):
+        if not self.schema:
+            return value
+
+        try:
+            self.schema.validate(value, resolver=resolver)
         except OpenAPISchemaError as exc:
             raise InvalidParameterValue(self.name, exc)
 
         try:
-            unmarshalled = self.schema.unmarshal(
-                casted,
+            return self.schema.unmarshal(
+                value,
                 custom_formatters=custom_formatters,
                 strict=True,
             )
         except OpenAPISchemaError as exc:
             raise InvalidParameterValue(self.name, exc)
-
-        try:
-            return self.schema.validate(
-                unmarshalled, custom_formatters=custom_formatters)
-        except OpenAPISchemaError as exc:
-            raise InvalidParameterValue(self.name, exc)
diff --git a/openapi_core/schema/schemas/_format.py b/openapi_core/schema/schemas/_format.py
new file mode 100644
index 0000000..e2af856
--- /dev/null
+++ b/openapi_core/schema/schemas/_format.py
@@ -0,0 +1,115 @@
+from base64 import b64encode, b64decode
+import binascii
+from datetime import datetime
+from uuid import UUID
+
+from jsonschema._format import FormatChecker
+from jsonschema.exceptions import FormatError
+from six import binary_type, text_type, integer_types
+
+DATETIME_HAS_STRICT_RFC3339 = False
+DATETIME_HAS_ISODATE = False
+DATETIME_RAISES = ()
+
+try:
+    import isodate
+except ImportError:
+    pass
+else:
+    DATETIME_HAS_ISODATE = True
+    DATETIME_RAISES += (ValueError, isodate.ISO8601Error)
+
+try:
+    import strict_rfc3339
+except ImportError:
+    pass
+else:
+    DATETIME_HAS_STRICT_RFC3339 = True
+    DATETIME_RAISES += (ValueError, TypeError)
+
+
+class StrictFormatChecker(FormatChecker):
+
+    def check(self, instance, format):
+        if format not in self.checkers:
+            raise FormatError(
+                "Format checker for %r format not found" % (format, ))
+        return super(StrictFormatChecker, self).check(
+            instance, format)
+
+
+oas30_format_checker = StrictFormatChecker()
+
+
+@oas30_format_checker.checks('int32')
+def is_int32(instance):
+    return isinstance(instance, integer_types)
+
+
+@oas30_format_checker.checks('int64')
+def is_int64(instance):
+    return isinstance(instance, integer_types)
+
+
+@oas30_format_checker.checks('float')
+def is_float(instance):
+    return isinstance(instance, float)
+
+
+@oas30_format_checker.checks('double')
+def is_double(instance):
+    # float has double precision in Python
+    # It's double in CPython and Jython
+    return isinstance(instance, float)
+
+
+@oas30_format_checker.checks('binary')
+def is_binary(instance):
+    return isinstance(instance, binary_type)
+
+
+@oas30_format_checker.checks('byte', raises=(binascii.Error, TypeError))
+def is_byte(instance):
+    if isinstance(instance, text_type):
+        instance = instance.encode()
+
+    return b64encode(b64decode(instance)) == instance
+
+
+@oas30_format_checker.checks("date-time", raises=DATETIME_RAISES)
+def is_datetime(instance):
+    if isinstance(instance, binary_type):
+        return False
+    if not isinstance(instance, text_type):
+        return True
+    
+    if DATETIME_HAS_STRICT_RFC3339:
+        return strict_rfc3339.validate_rfc3339(instance)
+    
+    if DATETIME_HAS_ISODATE:
+        return isodate.parse_datetime(instance)
+
+    return True
+
+
+@oas30_format_checker.checks("date", raises=ValueError)
+def is_date(instance):
+    if isinstance(instance, binary_type):
+        return False
+    if not isinstance(instance, text_type):
+        return True
+    return datetime.strptime(instance, "%Y-%m-%d")
+
+
+@oas30_format_checker.checks("uuid", raises=AttributeError)
+def is_uuid(instance):
+    if isinstance(instance, binary_type):
+        return False
+    if not isinstance(instance, text_type):
+        return True
+    try:
+        uuid_obj = UUID(instance)
+    except ValueError:
+        return False
+
+    return text_type(uuid_obj) == instance
diff --git a/openapi_core/schema/schemas/_types.py b/openapi_core/schema/schemas/_types.py
new file mode 100644
index 0000000..12d1d26
--- /dev/null
+++ b/openapi_core/schema/schemas/_types.py
@@ -0,0 +1,21 @@
+from jsonschema._types import (
+    TypeChecker, is_any, is_array, is_bool, is_integer,
+    is_object, is_number,
+)
+from six import text_type, binary_type
+
+
+def is_string(checker, instance):
+    return isinstance(instance, (text_type, binary_type))
+
+
+oas30_type_checker = TypeChecker(
+    {
+        u"string": is_string,
+        u"number": is_number,
+        u"integer": is_integer,
+        u"boolean": is_bool,
+        u"array": is_array,
+        u"object": is_object,
+    },
+)
diff --git a/openapi_core/schema/schemas/_validators.py b/openapi_core/schema/schemas/_validators.py
new file mode 100644
index 0000000..fc5a4ba
--- /dev/null
+++ b/openapi_core/schema/schemas/_validators.py
@@ -0,0 +1,58 @@
+from jsonschema._utils import find_additional_properties, extras_msg
+from jsonschema.exceptions import ValidationError, FormatError
+
+
+def type(validator, data_type, instance, schema):
+    if instance is None:
+        return
+
+    if not validator.is_type(instance, data_type):
+        yield ValidationError("%r is not of type %s" % (instance, data_type))
+
+
+def format(validator, format, instance, schema):
+    if instance is None:
+        return
+
+    if validator.format_checker is not None:
+        try:
+            validator.format_checker.check(instance, format)
+        except FormatError as error:
+            yield ValidationError(error.message, cause=error.cause)
+
+
+def items(validator, items, instance, schema):
+    if not validator.is_type(instance, "array"):
+        return
+
+    for index, item in enumerate(instance):
+        for error in validator.descend(item, items, path=index):
+            yield error
+
+
+def nullable(validator, is_nullable, instance, schema):
+    if instance is None and not is_nullable:
+        yield ValidationError("None for not nullable")
+
+
+def additionalProperties(validator, aP, instance, schema):
+    if not validator.is_type(instance, "object"):
+        return
+
+    extras = set(find_additional_properties(instance, schema))
+
+    if not extras:
+        return
+
+    if validator.is_type(aP, "object"):
+        for extra in extras:
+            for error in validator.descend(instance[extra], aP, path=extra):
+                yield error
+    elif validator.is_type(aP, "boolean"):
+        if not aP:
+            error = "Additional properties are not allowed (%s %s unexpected)"
+            yield ValidationError(error % extras_msg(extras))
+
+
+def not_implemented(validator, value, instance, schema):
+    pass
diff --git a/openapi_core/schema/schemas/exceptions.py b/openapi_core/schema/schemas/exceptions.py
index c984578..2adcde5 100644
--- a/openapi_core/schema/schemas/exceptions.py
+++ b/openapi_core/schema/schemas/exceptions.py
@@ -66,22 +66,6 @@ class MissingSchemaProperty(OpenAPISchemaError):
         return "Missing schema property: {0}".format(self.property_name)
 
 
-@attr.s(hash=True)
-class NoOneOfSchema(OpenAPISchemaError):
-    type = attr.ib()
-
-    def __str__(self):
-        return "Exactly one valid schema type {0} should be valid, None found.".format(self.type)
-
-
-@attr.s(hash=True)
-class MultipleOneOfSchema(OpenAPISchemaError):
-    type = attr.ib()
-
-    def __str__(self):
-        return "Exactly one schema type {0} should be valid, more than one found".format(self.type)
-
-
 class UnmarshallerError(OpenAPIMappingError):
     pass
 
diff --git a/openapi_core/schema/schemas/factories.py b/openapi_core/schema/schemas/factories.py
index 136fbd0..b42fcbb 100644
--- a/openapi_core/schema/schemas/factories.py
+++ b/openapi_core/schema/schemas/factories.py
@@ -1,9 +1,12 @@
 """OpenAPI core schemas factories module"""
 import logging
 
+from six import iteritems
+
 from openapi_core.compat import lru_cache
 from openapi_core.schema.properties.generators import PropertiesGenerator
 from openapi_core.schema.schemas.models import Schema
+from openapi_core.schema.schemas.types import Contribution
 
 log = logging.getLogger(__name__)
 
@@ -50,11 +53,11 @@ class SchemaFactory(object):
 
         all_of = []
         if all_of_spec:
-            all_of = map(self.create, all_of_spec)
+            all_of = list(map(self.create, all_of_spec))
 
         one_of = []
         if one_of_spec:
-            one_of = map(self.create, one_of_spec)
+            one_of = list(map(self.create, one_of_spec))
 
         items = None
         if items_spec:
@@ -76,6 +79,7 @@ class SchemaFactory(object):
             exclusive_maximum=exclusive_maximum,
             exclusive_minimum=exclusive_minimum,
             min_properties=min_properties, max_properties=max_properties,
+            _source=schema_deref,
         )
 
     @property
@@ -85,3 +89,59 @@ class SchemaFactory(object):
 
     def _create_items(self, items_spec):
         return self.create(items_spec)
+
+
+class SchemaDictFactory(object):
+
+    contributions = (
+        Contribution('type', src_prop_attr='value'),
+        Contribution('format'),
+        Contribution('properties', is_dict=True, dest_default={}),
+        Contribution('required', dest_default=[]),
+        Contribution('default'),
+        Contribution('nullable', dest_default=False),
+        Contribution('all_of', dest_prop_name='allOf', is_list=True, dest_default=[]),
+        Contribution('one_of', dest_prop_name='oneOf', is_list=True, dest_default=[]),
+        Contribution('additional_properties', dest_prop_name='additionalProperties', dest_default=True),
+        Contribution('min_items', dest_prop_name='minItems'),
+        Contribution('max_items', dest_prop_name='maxItems'),
+        Contribution('min_length', dest_prop_name='minLength'),
+        Contribution('max_length', dest_prop_name='maxLength'),
+        Contribution('pattern', src_prop_attr='pattern'),
+        Contribution('unique_items', dest_prop_name='uniqueItems', dest_default=False),
+        Contribution('minimum'),
+        Contribution('maximum'),
+        Contribution('multiple_of', dest_prop_name='multipleOf'),
+        Contribution('exclusive_minimum', dest_prop_name='exclusiveMinimum', dest_default=False),
+        Contribution('exclusive_maximum', dest_prop_name='exclusiveMaximum', dest_default=False),
+        Contribution('min_properties', dest_prop_name='minProperties'),
+        Contribution('max_properties', dest_prop_name='maxProperties'),
+    )
+
+    def create(self, schema):
+        schema_dict = {}
+        for contrib in self.contributions:
+            self._contribute(schema, schema_dict, contrib)
+        return schema_dict
+
+    def _contribute(self, schema, schema_dict, contrib):
+        def src_map(x):
+            return getattr(x, '__dict__')
+        src_val = getattr(schema, contrib.src_prop_name)
+
+        if src_val and contrib.src_prop_attr:
+            src_val = getattr(src_val, contrib.src_prop_attr)
+
+        if contrib.is_list:
+            src_val = list(map(src_map, src_val))
+        if contrib.is_dict:
+            src_val = dict(
+                (k, src_map(v))
+                for k, v in iteritems(src_val)
+            )
+
+        if src_val == contrib.dest_default:
+            return
+
+        dest_prop_name = contrib.dest_prop_name or contrib.src_prop_name
+        schema_dict[dest_prop_name] = src_val
diff --git a/openapi_core/schema/schemas/models.py b/openapi_core/schema/schemas/models.py
index 5dfa329..44ca3e6 100644
--- a/openapi_core/schema/schemas/models.py
+++ b/openapi_core/schema/schemas/models.py
@@ -9,12 +9,14 @@ import re
 import warnings
 
 from six import iteritems, integer_types, binary_type, text_type
+from jsonschema.exceptions import ValidationError
 
 from openapi_core.extensions.models.factories import ModelFactory
+from openapi_core.schema.schemas._format import oas30_format_checker
 from openapi_core.schema.schemas.enums import SchemaFormat, SchemaType
 from openapi_core.schema.schemas.exceptions import (
     InvalidSchemaValue, UndefinedSchemaProperty, MissingSchemaProperty,
-    OpenAPISchemaError, NoOneOfSchema, MultipleOneOfSchema, NoValidSchema,
+    OpenAPISchemaError, NoValidSchema,
     UndefinedItemsSchema, InvalidCustomFormatSchemaValue, InvalidSchemaProperty,
     UnmarshallerStrictTypeError,
 )
@@ -22,9 +24,7 @@ from openapi_core.schema.schemas.util import (
     forcebool, format_date, format_datetime, format_byte, format_uuid,
     format_number,
 )
-from openapi_core.schema.schemas.validators import (
-    TypeValidator, AttributeValidator,
-)
+from openapi_core.schema.schemas.validators import OAS30Validator
 
 log = logging.getLogger(__name__)
 
@@ -47,36 +47,6 @@ class Schema(object):
     DEFAULT_UNMARSHAL_CALLABLE_GETTER = {
     }
 
-    STRING_FORMAT_CALLABLE_GETTER = {
-        SchemaFormat.NONE: Format(text_type, TypeValidator(text_type)),
-        SchemaFormat.PASSWORD: Format(text_type, TypeValidator(text_type)),
-        SchemaFormat.DATE: Format(
-            format_date, TypeValidator(date, exclude=datetime)),
-        SchemaFormat.DATETIME: Format(format_datetime, TypeValidator(datetime)),
-        SchemaFormat.BINARY: Format(binary_type, TypeValidator(binary_type)),
-        SchemaFormat.UUID: Format(format_uuid, TypeValidator(UUID)),
-        SchemaFormat.BYTE: Format(format_byte, TypeValidator(text_type)),
-    }
-
-    NUMBER_FORMAT_CALLABLE_GETTER = {
-        SchemaFormat.NONE: Format(format_number, TypeValidator(
-            integer_types + (float, ), exclude=bool)),
-        SchemaFormat.FLOAT: Format(float, TypeValidator(float)),
-        SchemaFormat.DOUBLE: Format(float, TypeValidator(float)),
-    }
-
-    TYPE_VALIDATOR_CALLABLE_GETTER = {
-        SchemaType.ANY: lambda x: True,
-        SchemaType.BOOLEAN: TypeValidator(bool),
-        SchemaType.INTEGER: TypeValidator(integer_types, exclude=bool),
-        SchemaType.NUMBER: TypeValidator(
-            integer_types + (float, ), exclude=bool),
-        SchemaType.STRING: TypeValidator(
-            text_type, date, datetime, binary_type, UUID),
-        SchemaType.ARRAY: TypeValidator(list, tuple),
-        SchemaType.OBJECT: AttributeValidator('__dict__'),
-    }
-
     def __init__(
             self, schema_type=None, model=None, properties=None, items=None,
             schema_format=None, required=None, default=None, nullable=False,
@@ -85,7 +55,7 @@ class Schema(object):
             min_length=None, max_length=None, pattern=None, unique_items=False,
             minimum=None, maximum=None, multiple_of=None,
             exclusive_minimum=False, exclusive_maximum=False,
-            min_properties=None, max_properties=None):
+            min_properties=None, max_properties=None, _source=None):
         self.type = SchemaType(schema_type)
         self.model = model
         self.properties = properties and dict(properties) or {}
@@ -119,6 +89,16 @@ class Schema(object):
         self._all_required_properties_cache = None
         self._all_optional_properties_cache = None
 
+        self._source = _source
+
+    @property
+    def __dict__(self):
+        return self._source or self.to_dict()
+
+    def to_dict(self):
+        from openapi_core.schema.schemas.factories import SchemaDictFactory
+        return SchemaDictFactory().create(self)
+
     def __getitem__(self, name):
         return self.properties[name]
 
@@ -214,6 +194,18 @@ class Schema(object):
 
         return defaultdict(lambda: lambda x: x, mapping)
 
+    def get_validator(self, resolver=None):
+        return OAS30Validator(
+            self.__dict__, resolver=resolver, format_checker=oas30_format_checker)
+
+    def validate(self, value, resolver=None):
+        validator = self.get_validator(resolver=resolver)
+        try:
+            return validator.validate(value)
+        except ValidationError:
+            # TODO: pass validation errors
+            raise InvalidSchemaValue("Value not valid for schema", value, self.type)
+
     def unmarshal(self, value, custom_formatters=None, strict=True):
         """Unmarshal parameter from the value."""
         if self.deprecated:
@@ -241,10 +233,7 @@ class Schema(object):
                 "Value {value} is not of type {type}", value, self.type)
         except ValueError:
             raise InvalidSchemaValue(
-                "Failed to cast value {value} to type {type}", value, self.type)
-
-        if unmarshalled is None and not self.required:
-            return None
+                "Failed to unmarshal value {value} to type {type}", value, self.type)
 
         return unmarshalled
 
@@ -283,11 +272,12 @@ class Schema(object):
                     continue
                 else:
                     if result is not None:
-                        raise MultipleOneOfSchema(self.type)
+                        log.warning("multiple valid oneOf schemas found")
+                        continue
                     result = unmarshalled
 
             if result is None:
-                raise NoOneOfSchema(self.type)
+                log.warning("valid oneOf schema not found")
 
             return result
         else:
@@ -297,19 +287,16 @@ class Schema(object):
                     return unmarshal_callable(value)
                 except UnmarshallerStrictTypeError:
                     continue
-                # @todo: remove ValueError when validation separated
-                except (OpenAPISchemaError, TypeError, ValueError):
+                except (OpenAPISchemaError, TypeError):
                     continue
 
-        raise NoValidSchema(value)
+        log.warning("failed to unmarshal any type")
+        return value
 
     def _unmarshal_collection(self, value, custom_formatters=None, strict=True):
         if not isinstance(value, (list, tuple)):
             raise InvalidSchemaValue("Value {value} is not of type {type}", value, self.type)
 
-        if self.items is None:
-            raise UndefinedItemsSchema(self.type)
-
         f = functools.partial(
             self.items.unmarshal,
             custom_formatters=custom_formatters, strict=strict,
@@ -327,17 +314,18 @@ class Schema(object):
             properties = None
             for one_of_schema in self.one_of:
                 try:
-                    found_props = self._unmarshal_properties(
+                    unmarshalled = self._unmarshal_properties(
                         value, one_of_schema, custom_formatters=custom_formatters)
                 except OpenAPISchemaError:
                     pass
                 else:
                     if properties is not None:
-                        raise MultipleOneOfSchema(self.type)
-                    properties = found_props
+                        log.warning("multiple valid oneOf schemas found")
+                        continue
+                    properties = unmarshalled
 
             if properties is None:
-                raise NoOneOfSchema(self.type)
+                log.warning("valid oneOf schema not found")
 
         else:
             properties = self._unmarshal_properties(
@@ -381,242 +369,8 @@ class Schema(object):
                 if not prop.nullable and not prop.default:
                     continue
                 prop_value = prop.default
-            try:
-                properties[prop_name] = prop.unmarshal(
-                  prop_value, custom_formatters=custom_formatters)
-            except OpenAPISchemaError as exc:
-                raise InvalidSchemaProperty(prop_name, exc)
 
-        self._validate_properties(properties, one_of_schema=one_of_schema,
-                                  custom_formatters=custom_formatters)
+            properties[prop_name] = prop.unmarshal(
+                prop_value, custom_formatters=custom_formatters)
 
         return properties
-
-    def get_validator_mapping(self):
-        mapping = {
-            SchemaType.ARRAY: self._validate_collection,
-            SchemaType.STRING: self._validate_string,
-            SchemaType.OBJECT: self._validate_object,
-            SchemaType.INTEGER: self._validate_number,
-            SchemaType.NUMBER: self._validate_number,
-        }
-
-        def default(x, **kw):
-            return x
-
-        return defaultdict(lambda: default, mapping)
-
-    def validate(self, value, custom_formatters=None):
-        if value is None:
-            if not self.nullable:
-                raise InvalidSchemaValue("Null value for non-nullable schema of type {type}", value, self.type)
-            return
-
-        # type validation
-        type_validator_callable = self.TYPE_VALIDATOR_CALLABLE_GETTER[
-            self.type]
-        if not type_validator_callable(value):
-            raise InvalidSchemaValue(
-                "Value {value} not valid type {type}", value, self.type.value)
-
-        # structure validation
-        validator_mapping = self.get_validator_mapping()
-        validator_callable = validator_mapping[self.type]
-        validator_callable(value, custom_formatters=custom_formatters)
-
-        return value
-
-    def _validate_collection(self, value, custom_formatters=None):
-        if self.items is None:
-            raise UndefinedItemsSchema(self.type)
-
-        if self.min_items is not None:
-            if self.min_items < 0:
-                raise OpenAPISchemaError(
-                    "Schema for collection invalid:"
-                    " minItems must be non-negative"
-                )
-            if len(value) < self.min_items:
-                raise InvalidSchemaValue(
-                    "Value must contain at least {type} item(s),"
-                    " {value} found", len(value), self.min_items)
-        if self.max_items is not None:
-            if self.max_items < 0:
-                raise OpenAPISchemaError(
-                    "Schema for collection invalid:"
-                    " maxItems must be non-negative"
-                )
-            if len(value) > self.max_items:
-                raise InvalidSchemaValue(
-                    "Value must contain at most {value} item(s),"
-                    " {type} found", len(value), self.max_items)
-        if self.unique_items and len(set(value)) != len(value):
-            raise OpenAPISchemaError("Value may not contain duplicate items")
-
-        f = functools.partial(self.items.validate,
-                              custom_formatters=custom_formatters)
-        return list(map(f, value))
-
-    def _validate_number(self, value, custom_formatters=None):
-        if self.minimum is not None:
-            if self.exclusive_minimum and value <= self.minimum:
-                raise InvalidSchemaValue(
-                    "Value {value} is not less than or equal to {type}", value, self.minimum)
-            elif value < self.minimum:
-                raise InvalidSchemaValue(
-                    "Value {value} is not less than {type}", value, self.minimum)
-
-        if self.maximum is not None:
-            if self.exclusive_maximum and value >= self.maximum:
-                raise InvalidSchemaValue(
-                    "Value {value} is not greater than or equal to {type}", value, self.maximum)
-            elif value > self.maximum:
-                raise InvalidSchemaValue(
-                    "Value {value} is not greater than {type}", value, self.maximum)
-
-        if self.multiple_of is not None and value % self.multiple_of:
-            raise InvalidSchemaValue(
-                "Value {value} is not a multiple of {type}",
-                    value, self.multiple_of)
-
-    def _validate_string(self, value, custom_formatters=None):
-        try:
-            schema_format = SchemaFormat(self.format)
-        except ValueError:
-            msg = "Unsupported {0} format validation".format(self.format)
-            if custom_formatters is not None:
-                formatstring = custom_formatters.get(self.format)
-                if formatstring is None:
-                    raise OpenAPISchemaError(msg)
-            else:
-                raise OpenAPISchemaError(msg)
-        else:
-            formatstring =\
-                self.STRING_FORMAT_CALLABLE_GETTER[schema_format]
-
-        if not formatstring.validate(value):
-            raise InvalidSchemaValue(
-                "Value {value} not valid format {type}", value, self.format)
-
-        if self.min_length is not None:
-            if self.min_length < 0:
-                raise OpenAPISchemaError(
-                    "Schema for string invalid:"
-                    " minLength must be non-negative"
-                )
-            if len(value) < self.min_length:
-                raise InvalidSchemaValue(
-                    "Value is shorter ({value}) than the minimum length of {type}",
-                    len(value), self.min_length
-                )
-        if self.max_length is not None:
-            if self.max_length < 0:
-                raise OpenAPISchemaError(
-                    "Schema for string invalid:"
-                    " maxLength must be non-negative"
-                )
-            if len(value) > self.max_length:
-                raise InvalidSchemaValue(
-                    "Value is longer ({value}) than the maximum length of {type}",
-                    len(value), self.max_length
-                )
-        if self.pattern is not None and not self.pattern.search(value):
-            raise InvalidSchemaValue(
-                "Value {value} does not match the pattern {type}",
-                    value, self.pattern.pattern
-            )
-
-        return True
-
-    def _validate_object(self, value, custom_formatters=None):
-        properties = value.__dict__
-
-        if self.one_of:
-            valid_one_of_schema = None
-            for one_of_schema in self.one_of:
-                try:
-                    self._validate_properties(
-                      properties, one_of_schema,
-                      custom_formatters=custom_formatters)
-                except OpenAPISchemaError:
-                    pass
-                else:
-                    if valid_one_of_schema is not None:
-                        raise MultipleOneOfSchema(self.type)
-                    valid_one_of_schema = True
-
-            if valid_one_of_schema is None:
-                raise NoOneOfSchema(self.type)
-
-        else:
-            self._validate_properties(properties,
-                                      custom_formatters=custom_formatters)
-
-        if self.min_properties is not None:
-            if self.min_properties < 0:
-                raise OpenAPISchemaError(
-                    "Schema for object invalid:"
-                    " minProperties must be non-negative"
-                )
-
-            if len(properties) < self.min_properties:
-                raise InvalidSchemaValue(
-                    "Value must contain at least {type} properties,"
-                    " {value} found", len(properties), self.min_properties
-                )
-
-        if self.max_properties is not None:
-            if self.max_properties < 0:
-                raise OpenAPISchemaError(
-                    "Schema for object invalid:"
-                    " maxProperties must be non-negative"
-                )
-            if len(properties) > self.max_properties:
-                raise InvalidSchemaValue(
-                    "Value must contain at most {type} properties,"
-                    " {value} found", len(properties), self.max_properties
-                )
-
-        return True
-
-    def _validate_properties(self, value, one_of_schema=None,
-                             custom_formatters=None):
-        all_props = self.get_all_properties()
-        all_props_names = self.get_all_properties_names()
-        all_req_props_names = self.get_all_required_properties_names()
-
-        if one_of_schema is not None:
-            all_props.update(one_of_schema.get_all_properties())
-            all_props_names |= one_of_schema.\
-                get_all_properties_names()
-            all_req_props_names |= one_of_schema.\
-                get_all_required_properties_names()
-
-        value_props_names = value.keys()
-        extra_props = set(value_props_names) - set(all_props_names)
-        extra_props_allowed = self.are_additional_properties_allowed(
-            one_of_schema)
-        if extra_props and not extra_props_allowed:
-            raise UndefinedSchemaProperty(extra_props)
-
-        if self.additional_properties is not True:
-            for prop_name in extra_props:
-                prop_value = value[prop_name]
-                self.additional_properties.validate(
-                    prop_value, custom_formatters=custom_formatters)
-
-        for prop_name, prop in iteritems(all_props):
-            try:
-                prop_value = value[prop_name]
-            except KeyError:
-                if prop_name in all_req_props_names:
-                    raise MissingSchemaProperty(prop_name)
-                if not prop.nullable and not prop.default:
-                    continue
-                prop_value = prop.default
-            try:
-                prop.validate(prop_value, custom_formatters=custom_formatters)
-            except OpenAPISchemaError as exc:
-                raise InvalidSchemaProperty(prop_name, original_exception=exc)
-
-        return True
diff --git a/openapi_core/schema/schemas/types.py b/openapi_core/schema/schemas/types.py
new file mode 100644
index 0000000..acfcae4
--- /dev/null
+++ b/openapi_core/schema/schemas/types.py
@@ -0,0 +1,11 @@
+import attr
+
+
+@attr.s(hash=True)
+class Contribution(object):
+    src_prop_name = attr.ib()
+    src_prop_attr = attr.ib(default=None)
+    dest_prop_name = attr.ib(default=None)
+    is_list = attr.ib(default=False)
+    is_dict = attr.ib(default=False)
+    dest_default = attr.ib(default=None)
diff --git a/openapi_core/schema/schemas/unmarshallers.py b/openapi_core/schema/schemas/unmarshallers.py
index 86fd46b..31ba5b6 100644
--- a/openapi_core/schema/schemas/unmarshallers.py
+++ b/openapi_core/schema/schemas/unmarshallers.py
@@ -3,7 +3,7 @@ from six import text_type, binary_type, integer_types
 from openapi_core.schema.schemas.enums import SchemaFormat, SchemaType
 from openapi_core.schema.schemas.exceptions import (
     InvalidSchemaValue, InvalidCustomFormatSchemaValue,
-    OpenAPISchemaError, MultipleOneOfSchema, NoOneOfSchema,
+    OpenAPISchemaError,
     InvalidSchemaProperty,
     UnmarshallerStrictTypeError,
 )
diff --git a/openapi_core/schema/schemas/validators.py b/openapi_core/schema/schemas/validators.py
index 2d9ec49..52cf1dc 100644
--- a/openapi_core/schema/schemas/validators.py
+++ b/openapi_core/schema/schemas/validators.py
@@ -1,26 +1,67 @@
-class TypeValidator(object):
+from jsonschema import _legacy_validators, _format, _types, _utils, _validators
+from jsonschema.validators import create
 
-    def __init__(self, *types, **options):
-        self.types = types
-        self.exclude = options.get('exclude')
-
-    def __call__(self, value):
-        if self.exclude is not None and isinstance(value, self.exclude):
-            return False
-
-        if not isinstance(value, self.types):
-            return False
-
-        return True
+from openapi_core.schema.schemas import _types as oas_types
+from openapi_core.schema.schemas import _validators as oas_validators
 
 
-class AttributeValidator(object):
+BaseOAS30Validator = create(
+    meta_schema=_utils.load_schema("draft4"),
+    validators={
+        u"multipleOf": _validators.multipleOf,
+        # exclusiveMaximum supported inside maximum_draft3_draft4
+        u"maximum": _legacy_validators.maximum_draft3_draft4,
+        # exclusiveMinimum supported inside minimum_draft3_draft4
+        u"minimum": _legacy_validators.minimum_draft3_draft4,
+        u"maxLength": _validators.maxLength,
+        u"minLength": _validators.minLength,
+        u"pattern": _validators.pattern,
+        u"maxItems": _validators.maxItems,
+        u"minItems": _validators.minItems,
+        u"uniqueItems": _validators.uniqueItems,
+        u"maxProperties": _validators.maxProperties,
+        u"minProperties": _validators.minProperties,
+        u"required": _validators.required,
+        u"enum": _validators.enum,
+        # adjusted to OAS
+        u"type": oas_validators.type,
+        u"allOf": _validators.allOf,
+        u"oneOf": _validators.oneOf,
+        u"anyOf": _validators.anyOf,
+        u"not": _validators.not_,
+        u"items": oas_validators.items,
+        u"properties": _validators.properties,
+        u"additionalProperties": oas_validators.additionalProperties,
+        # TODO: adjust description
+        u"format": oas_validators.format,
+        # TODO: adjust default
+        u"$ref": _validators.ref,
+        # fixed OAS fields
+        u"nullable": oas_validators.nullable,
+        u"discriminator": oas_validators.not_implemented,
+        u"readOnly": oas_validators.not_implemented,
+        u"writeOnly": oas_validators.not_implemented,
+        u"xml": oas_validators.not_implemented,
+        u"externalDocs": oas_validators.not_implemented,
+        u"example": oas_validators.not_implemented,
+        u"deprecated": oas_validators.not_implemented,
+    },
+    type_checker=oas_types.oas30_type_checker,
+    version="oas30",
+    id_of=lambda schema: schema.get(u"id", ""),
+)
 
-    def __init__(self, attribute):
-        self.attribute = attribute
 
-    def __call__(self, value):
-        if not hasattr(value, self.attribute):
-            return False
+class OAS30Validator(BaseOAS30Validator):
 
-        return True
+    def iter_errors(self, instance, _schema=None):
+        if _schema is None:
+                _schema = self.schema
+
+        # append defaults to trigger validator (i.e. nullable)
+        if 'nullable' not in _schema:
+            _schema.update({
+                'nullable': False,
+            })
+
+        return super(OAS30Validator, self).iter_errors(instance, _schema)
diff --git a/openapi_core/schema/specs/factories.py b/openapi_core/schema/specs/factories.py
index 16f736d..0d31dd6 100644
--- a/openapi_core/schema/specs/factories.py
+++ b/openapi_core/schema/specs/factories.py
@@ -2,6 +2,7 @@
 """OpenAPI core specs factories module"""
 
 from openapi_spec_validator import openapi_v3_spec_validator
+from openapi_spec_validator.validators import Dereferencer
 
 from openapi_core.compat import lru_cache
 from openapi_core.schema.components.factories import ComponentsFactory
@@ -14,8 +15,8 @@ from openapi_core.schema.specs.models import Spec
 
 class SpecFactory(object):
 
-    def __init__(self, dereferencer, config=None):
-        self.dereferencer = dereferencer
+    def __init__(self, spec_resolver, config=None):
+        self.spec_resolver = spec_resolver
         self.config = config or {}
 
     def create(self, spec_dict, spec_url=''):
@@ -34,9 +35,16 @@ class SpecFactory(object):
         paths = self.paths_generator.generate(paths)
         components = self.components_factory.create(components_spec)
         spec = Spec(
-            info, list(paths), servers=list(servers), components=components)
+            info, list(paths), servers=list(servers), components=components,
+            _resolver=self.spec_resolver,
+        )
         return spec
 
+    @property
+    @lru_cache()
+    def dereferencer(self):
+        return Dereferencer(self.spec_resolver)
+
     @property
     @lru_cache()
     def schemas_registry(self):
diff --git a/openapi_core/schema/specs/models.py b/openapi_core/schema/specs/models.py
index 7e7c4e1..f4a115e 100644
--- a/openapi_core/schema/specs/models.py
+++ b/openapi_core/schema/specs/models.py
@@ -14,12 +14,14 @@ log = logging.getLogger(__name__)
 class Spec(object):
     """Represents an OpenAPI Specification for a service."""
 
-    def __init__(self, info, paths, servers=None, components=None):
+    def __init__(self, info, paths, servers=None, components=None, _resolver=None):
         self.info = info
         self.paths = paths and dict(paths)
         self.servers = servers or []
         self.components = components
 
+        self._resolver = _resolver
+
     def __getitem__(self, path_pattern):
         return self.get_path(path_pattern)
 
diff --git a/openapi_core/shortcuts.py b/openapi_core/shortcuts.py
index bcf4d31..02df1c1 100644
--- a/openapi_core/shortcuts.py
+++ b/openapi_core/shortcuts.py
@@ -1,6 +1,5 @@
 """OpenAPI core shortcuts module"""
 from jsonschema.validators import RefResolver
-from openapi_spec_validator.validators import Dereferencer
 from openapi_spec_validator import default_handlers
 
 from openapi_core.schema.media_types.exceptions import OpenAPIMediaTypeError
@@ -17,8 +16,7 @@ from openapi_core.validation.response.validators import ResponseValidator
 def create_spec(spec_dict, spec_url=''):
     spec_resolver = RefResolver(
         spec_url, spec_dict, handlers=default_handlers)
-    dereferencer = Dereferencer(spec_resolver)
-    spec_factory = SpecFactory(dereferencer)
+    spec_factory = SpecFactory(spec_resolver)
     return spec_factory.create(spec_dict, spec_url=spec_url)
 
 
diff --git a/openapi_core/validation/request/validators.py b/openapi_core/validation/request/validators.py
index 734b589..ba4851e 100644
--- a/openapi_core/validation/request/validators.py
+++ b/openapi_core/validation/request/validators.py
@@ -58,7 +58,7 @@ class RequestValidator(object):
                 continue
             seen.add((param_name, param.location.value))
             try:
-                raw_value = param.get_value(request)
+                raw_value = param.get_raw_value(request)
             except MissingParameter:
                 continue
             except OpenAPIMappingError as exc:
@@ -66,11 +66,20 @@ class RequestValidator(object):
                 continue
 
             try:
-                value = param.unmarshal(raw_value, self.custom_formatters)
+                casted = param.cast(raw_value)
+            except OpenAPIMappingError as exc:
+                errors.append(exc)
+                continue
+
+            try:
+                unmarshalled = param.unmarshal(
+                    casted, self.custom_formatters,
+                    resolver=self.spec._resolver,
+                )
             except OpenAPIMappingError as exc:
                 errors.append(exc)
             else:
-                parameters[param.location.value][param_name] = value
+                parameters[param.location.value][param_name] = unmarshalled
 
         return parameters, errors
 
@@ -92,8 +101,16 @@ class RequestValidator(object):
                 errors.append(exc)
             else:
                 try:
-                    body = media_type.unmarshal(raw_body, self.custom_formatters)
+                    casted = media_type.cast(raw_body)
                 except OpenAPIMappingError as exc:
                     errors.append(exc)
+                else:
+                    try:
+                        body = media_type.unmarshal(
+                            casted, self.custom_formatters,
+                            resolver=self.spec._resolver,
+                        )
+                    except OpenAPIMappingError as exc:
+                        errors.append(exc)
 
         return body, errors
diff --git a/openapi_core/validation/response/validators.py b/openapi_core/validation/response/validators.py
index 4f9696b..2ed923a 100644
--- a/openapi_core/validation/response/validators.py
+++ b/openapi_core/validation/response/validators.py
@@ -61,9 +61,17 @@ class ResponseValidator(object):
                 errors.append(exc)
             else:
                 try:
-                    data = media_type.unmarshal(raw_data, self.custom_formatters)
+                    casted = media_type.cast(raw_data)
                 except OpenAPIMappingError as exc:
                     errors.append(exc)
+                else:
+                    try:
+                        data = media_type.unmarshal(
+                            casted, self.custom_formatters,
+                            resolver=self.spec._resolver,
+                        )
+                    except OpenAPIMappingError as exc:
+                        errors.append(exc)
 
         return data, errors
 
diff --git a/requirements.txt b/requirements.txt
index 1141546..de7efe3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,4 +2,5 @@ openapi-spec-validator
 six
 lazy-object-proxy
 strict_rfc3339
+isodate
 attrs
diff --git a/tests/integration/data/v3.0/petstore.yaml b/tests/integration/data/v3.0/petstore.yaml
index efd817d..5f42339 100644
--- a/tests/integration/data/v3.0/petstore.yaml
+++ b/tests/integration/data/v3.0/petstore.yaml
@@ -317,7 +317,10 @@ components:
             suberror:
               $ref: "#/components/schemas/ExtendedError"
       additionalProperties:
-        type: string
+        oneOf:
+          - type: string
+          - type: integer
+            format: int32
   responses:
     ErrorResponse:
       description: unexpected error
diff --git a/tests/integration/test_petstore.py b/tests/integration/test_petstore.py
index 4c92c91..5e57c5e 100644
--- a/tests/integration/test_petstore.py
+++ b/tests/integration/test_petstore.py
@@ -19,9 +19,7 @@ from openapi_core.schema.paths.models import Path
 from openapi_core.schema.request_bodies.models import RequestBody
 from openapi_core.schema.responses.models import Response
 from openapi_core.schema.schemas.enums import SchemaType
-from openapi_core.schema.schemas.exceptions import (
-    InvalidSchemaProperty, InvalidSchemaValue,
-)
+from openapi_core.schema.schemas.exceptions import InvalidSchemaValue
 from openapi_core.schema.schemas.models import Schema
 from openapi_core.schema.servers.exceptions import InvalidServer
 from openapi_core.schema.servers.models import Server, ServerVariable
@@ -41,13 +39,17 @@ class TestPetstore(object):
         api_key_bytes_enc = b64encode(api_key_bytes)
         return text_type(api_key_bytes_enc, 'utf8')
 
+    @pytest.fixture
+    def spec_uri(self):
+        return "file://tests/integration/data/v3.0/petstore.yaml"
+
     @pytest.fixture
     def spec_dict(self, factory):
         return factory.spec_from_file("data/v3.0/petstore.yaml")
 
     @pytest.fixture
-    def spec(self, spec_dict):
-        return create_spec(spec_dict)
+    def spec(self, spec_dict, spec_uri):
+        return create_spec(spec_dict, spec_uri)
 
     @pytest.fixture
     def request_validator(self, spec):
@@ -267,6 +269,9 @@ class TestPetstore(object):
                 {
                     'id': 1,
                     'name': 'Cat',
+                    'ears': {
+                        'healthy': True,
+                    },
                 }
             ],
         }
@@ -322,16 +327,10 @@ class TestPetstore(object):
 
         assert response_result.errors == [
             InvalidMediaTypeValue(
-                original_exception=InvalidSchemaProperty(
-                    property_name='data',
-                    original_exception=InvalidSchemaProperty(
-                        property_name='name',
-                        original_exception=InvalidSchemaValue(
-                            msg="Value {value} is not of type {type}",
-                            type=SchemaType.STRING,
-                            value={'first_name': 'Cat'},
-                        ),
-                    ),
+                original_exception=InvalidSchemaValue(
+                    msg='Value not valid for schema',
+                    type=SchemaType.OBJECT,
+                    value=data_json,
                 ),
             ),
         ]
@@ -932,6 +931,9 @@ class TestPetstore(object):
             'data': {
                 'id': data_id,
                 'name': data_name,
+                'ears': {
+                    'healthy': True,
+                },
             },
         }
         data = json.dumps(data_json)
@@ -1239,7 +1241,6 @@ class TestPetstore(object):
         assert response_result.data.rootCause == rootCause
         assert response_result.data.additionalinfo == additionalinfo
 
-    @pytest.mark.xfail(reason='OneOf for string not supported atm')
     def test_post_tags_created_invalid_type(
             self, spec, response_validator):
         host_url = 'http://petstore.swagger.io/v1'
diff --git a/tests/integration/test_validators.py b/tests/integration/test_validators.py
index 2f26a7b..2d3af8f 100644
--- a/tests/integration/test_validators.py
+++ b/tests/integration/test_validators.py
@@ -421,6 +421,17 @@ class TestResponseValidator(object):
         assert result.data is None
         assert result.headers == {}
 
+    def test_invalid_media_type(self, validator):
+        request = MockRequest(self.host_url, 'get', '/v1/pets')
+        response = MockResponse("abcde")
+
+        result = validator.validate(request, response)
+
+        assert len(result.errors) == 1
+        assert type(result.errors[0]) == InvalidMediaTypeValue
+        assert result.data is None
+        assert result.headers == {}
+
     def test_invalid_media_type_value(self, validator):
         request = MockRequest(self.host_url, 'get', '/v1/pets')
         response = MockResponse("{}")
@@ -458,7 +469,10 @@ class TestResponseValidator(object):
             'data': [
                 {
                     'id': 1,
-                    'name': 'Sparky'
+                    'name': 'Sparky',
+                    'ears': {
+                        'healthy': True,
+                    },
                 },
             ],
         }
diff --git a/tests/unit/schema/test_media_types.py b/tests/unit/schema/test_media_types.py
new file mode 100644
index 0000000..2d266ac
--- /dev/null
+++ b/tests/unit/schema/test_media_types.py
@@ -0,0 +1,53 @@
+import pytest
+
+from openapi_core.schema.media_types.exceptions import InvalidMediaTypeValue
+from openapi_core.schema.media_types.models import MediaType
+from openapi_core.schema.schemas.models import Schema
+
+
+class TestMediaTypeCast(object):
+
+    def test_empty(self):
+        media_type = MediaType('application/json')
+        value = ''
+
+        result = media_type.cast(value)
+
+        assert result == value
+
+
+class TestParameterUnmarshal(object):
+
+    def test_empty(self):
+        media_type = MediaType('application/json')
+        value = ''
+
+        result = media_type.unmarshal(value)
+
+        assert result == value
+
+    def test_schema_type_invalid(self):
+        schema = Schema('integer', _source={'type': 'integer'})
+        media_type = MediaType('application/json', schema=schema)
+        value = 'test'
+
+        with pytest.raises(InvalidMediaTypeValue):
+            media_type.unmarshal(value)
+
+    def test_schema_custom_format_invalid(self):
+        def custom_formatter(value):
+            raise ValueError
+        schema = Schema(
+            'string',
+            schema_format='custom',
+            _source={'type': 'string', 'format': 'custom'},
+        )
+        custom_formatters = {
+            'custom': custom_formatter,
+        }
+        media_type = MediaType('application/json', schema=schema)
+        value = 'test'
+
+        with pytest.raises(InvalidMediaTypeValue):
+            media_type.unmarshal(
+                value, custom_formatters=custom_formatters)
diff --git a/tests/unit/schema/test_parameters.py b/tests/unit/schema/test_parameters.py
index 952e956..2755dcb 100644
--- a/tests/unit/schema/test_parameters.py
+++ b/tests/unit/schema/test_parameters.py
@@ -1,8 +1,11 @@
 import pytest
 
-from openapi_core.schema.parameters.exceptions import EmptyParameterValue
+from openapi_core.schema.parameters.exceptions import (
+    EmptyParameterValue, InvalidParameterValue,
+)
 from openapi_core.schema.parameters.enums import ParameterStyle
 from openapi_core.schema.parameters.models import Parameter
+from openapi_core.schema.schemas.models import Schema
 
 
 class TestParameterInit(object):
@@ -36,17 +39,35 @@ class TestParameterInit(object):
         assert param.explode is True
 
 
-class TestParameterUnmarshal(object):
+class TestParameterCast(object):
 
     def test_deprecated(self):
         param = Parameter('param', 'query', deprecated=True)
         value = 'test'
 
         with pytest.warns(DeprecationWarning):
-            result = param.unmarshal(value)
+            result = param.cast(value)
 
         assert result == value
 
+    def test_query_empty(self):
+        param = Parameter('param', 'query')
+        value = ''
+
+        with pytest.raises(EmptyParameterValue):
+            param.cast(value)
+
+    def test_query_valid(self):
+        param = Parameter('param', 'query')
+        value = 'test'
+
+        result = param.cast(value)
+
+        assert result == value
+
+
+class TestParameterUnmarshal(object):
+
     def test_query_valid(self):
         param = Parameter('param', 'query')
         value = 'test'
@@ -55,13 +76,6 @@ class TestParameterUnmarshal(object):
 
         assert result == value
 
-    def test_query_empty(self):
-        param = Parameter('param', 'query')
-        value = ''
-
-        with pytest.raises(EmptyParameterValue):
-            param.unmarshal(value)
-
     def test_query_allow_empty_value(self):
         param = Parameter('param', 'query', allow_empty_value=True)
         value = ''
@@ -69,3 +83,28 @@ class TestParameterUnmarshal(object):
         result = param.unmarshal(value)
 
         assert result == value
+
+    def test_query_schema_type_invalid(self):
+        schema = Schema('integer', _source={'type': 'integer'})
+        param = Parameter('param', 'query', schema=schema)
+        value = 'test'
+
+        with pytest.raises(InvalidParameterValue):
+            param.unmarshal(value)
+
+    def test_query_schema_custom_format_invalid(self):
+        def custom_formatter(value):
+            raise ValueError
+        schema = Schema(
+            'string',
+            schema_format='custom',
+            _source={'type': 'string', 'format': 'custom'},
+        )
+        custom_formatters = {
+            'custom': custom_formatter,
+        }
+        param = Parameter('param', 'query', schema=schema)
+        value = 'test'
+
+        with pytest.raises(InvalidParameterValue):
+            param.unmarshal(value, custom_formatters=custom_formatters)
diff --git a/tests/unit/schema/test_schemas.py b/tests/unit/schema/test_schemas.py
index 0b747aa..f8d9a88 100644
--- a/tests/unit/schema/test_schemas.py
+++ b/tests/unit/schema/test_schemas.py
@@ -7,8 +7,7 @@ import pytest
 from openapi_core.extensions.models.models import Model
 from openapi_core.schema.schemas.enums import SchemaFormat, SchemaType
 from openapi_core.schema.schemas.exceptions import (
-    InvalidSchemaValue, MultipleOneOfSchema, NoOneOfSchema, OpenAPISchemaError,
-    UndefinedSchemaProperty
+    InvalidSchemaValue, OpenAPISchemaError,
 )
 from openapi_core.schema.schemas.models import Schema
 
@@ -42,6 +41,17 @@ class TestSchemaUnmarshal(object):
 
         assert result == value
 
+    @pytest.mark.parametrize('schema_type', [
+        'boolean', 'array', 'integer', 'number',
+    ])
+    def test_non_string_empty_value(self, schema_type):
+        schema = Schema(schema_type)
+        value = ''
+
+        result = schema.unmarshal(value)
+
+        assert result is None
+
     def test_string_valid(self):
         schema = Schema('string')
         value = 'test'
@@ -121,19 +131,28 @@ class TestSchemaUnmarshal(object):
 
         assert result == datetime.datetime(2018, 1, 2, 0, 0)
 
-    @pytest.mark.xfail(reason="No custom formats support atm")
     def test_string_format_custom(self):
+        def custom_formatter(value):
+            return 'x-custom'
         custom_format = 'custom'
         schema = Schema('string', schema_format=custom_format)
         value = 'x'
 
-        with mock.patch.dict(
-            Schema.STRING_FORMAT_CAST_CALLABLE_GETTER,
-            {custom_format: lambda x: x + '-custom'},
-        ):
-            result = schema.unmarshal(value)
+        result = schema.unmarshal(
+            value, custom_formatters={custom_format: custom_formatter})
 
-        assert result == 'x-custom'
+        assert result == custom_formatter(value)
+
+    def test_string_format_custom_value_error(self):
+        def custom_formatter(value):
+            raise ValueError
+        custom_format = 'custom'
+        schema = Schema('string', schema_format=custom_format)
+        value = 'x'
+
+        with pytest.raises(InvalidSchemaValue):
+            schema.unmarshal(
+                value, custom_formatters={custom_format: custom_formatter})
 
     def test_string_format_unknown(self):
         unknown_format = 'unknown'
@@ -143,16 +162,12 @@ class TestSchemaUnmarshal(object):
         with pytest.raises(OpenAPISchemaError):
             schema.unmarshal(value)
 
-    @pytest.mark.xfail(reason="No custom formats support atm")
     def test_string_format_invalid_value(self):
         custom_format = 'custom'
         schema = Schema('string', schema_format=custom_format)
         value = 'x'
 
-        with mock.patch.dict(
-            Schema.STRING_FORMAT_CALLABLE_GETTER,
-            {custom_format: mock.Mock(side_effect=ValueError())},
-        ), pytest.raises(
+        with pytest.raises(
             InvalidSchemaValue, message='Failed to format value'
         ):
             schema.unmarshal(value)
@@ -307,22 +322,6 @@ class TestSchemaUnmarshal(object):
         ])
         assert schema.unmarshal(['hello']) == ['hello']
 
-    def test_schema_any_one_of_mutiple(self):
-        schema = Schema(one_of=[
-            Schema('array', items=Schema('string')),
-            Schema('array', items=Schema('number')),
-        ])
-        with pytest.raises(MultipleOneOfSchema):
-            schema.unmarshal([])
-
-    def test_schema_any_one_of_no_valid(self):
-        schema = Schema(one_of=[
-            Schema('array', items=Schema('string')),
-            Schema('array', items=Schema('number')),
-        ])
-        with pytest.raises(NoOneOfSchema):
-            schema.unmarshal({})
-
     def test_schema_any(self):
         schema = Schema()
         assert schema.unmarshal('string') == 'string'
@@ -351,13 +350,23 @@ class TestSchemaValidate(object):
 
         assert result is None
 
+    @pytest.mark.xfail(
+        reason="validation does not care about custom formats atm")
+    def test_string_format_custom_missing(self):
+        custom_format = 'custom'
+        schema = Schema('string', schema_format=custom_format)
+        value = 'x'
+
+        with pytest.raises(OpenAPISchemaError):
+            schema.validate(value)
+
     @pytest.mark.parametrize('value', [False, True])
     def test_boolean(self, value):
         schema = Schema('boolean')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [1, 3.14, u('true'), [True, False]])
     def test_boolean_invalid(self, value):
@@ -366,22 +375,22 @@ class TestSchemaValidate(object):
         with pytest.raises(InvalidSchemaValue):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [[1, 2], (3, 4)])
+    @pytest.mark.parametrize('value', [(1, 2)])
     def test_array_no_schema(self, value):
         schema = Schema('array')
 
         with pytest.raises(OpenAPISchemaError):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [[1, 2], (3, 4)])
+    @pytest.mark.parametrize('value', [[1, 2]])
     def test_array(self, value):
         schema = Schema('array', items=Schema('integer'))
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
-    @pytest.mark.parametrize('value', [False, 1, 3.14, u('true')])
+    @pytest.mark.parametrize('value', [False, 1, 3.14, u('true'), (3, 4)])
     def test_array_invalid(self, value):
         schema = Schema('array')
 
@@ -394,7 +403,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [False, 3.14, u('true'), [1, 2]])
     def test_integer_invalid(self, value):
@@ -416,7 +425,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [4, 5, 6])
     def test_integer_maximum_invalid(self, value):
@@ -431,7 +440,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [1, 2, 4])
     def test_integer_multiple_of_invalid(self, value):
@@ -446,7 +455,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [1, 3.14])
     def test_number(self, value):
@@ -454,7 +463,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [False, 'true', [1, 3]])
     def test_number_invalid(self, value):
@@ -476,7 +485,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [1, 2, 3])
     def test_number_exclusive_minimum_invalid(self, value):
@@ -491,7 +500,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [4, 5, 6])
     def test_number_maximum_invalid(self, value):
@@ -506,7 +515,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [3, 4, 5])
     def test_number_exclusive_maximum_invalid(self, value):
@@ -521,7 +530,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [1, 2, 4])
     def test_number_multiple_of_invalid(self, value):
@@ -536,17 +545,17 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
-    @pytest.mark.parametrize('value', [u('true'), ])
+    @pytest.mark.parametrize('value', [u('true'), b('test')])
     def test_string(self, value):
         schema = Schema('string')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
-    @pytest.mark.parametrize('value', [b('test'), False, 1, 3.14, [1, 3]])
+    @pytest.mark.parametrize('value', [False, 1, 3.14, [1, 3]])
     def test_string_invalid(self, value):
         schema = Schema('string')
 
@@ -564,24 +573,24 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        datetime.date(1989, 1, 2), datetime.date(2018, 1, 2),
+        u('1989-01-02'), u('2018-01-02'),
     ])
     def test_string_format_date(self, value):
         schema = Schema('string', schema_format='date')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [
-        uuid.UUID('{12345678-1234-5678-1234-567812345678}'),
+        u('12345678-1234-5678-1234-567812345678'),
     ])
     def test_string_format_uuid(self, value):
         schema = Schema('string', schema_format='uuid')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [
         b('true'), u('true'), False, 1, 3.14, [1, 3],
@@ -595,7 +604,7 @@ class TestSchemaValidate(object):
 
     @pytest.mark.parametrize('value', [
         b('true'), u('true'), False, 1, 3.14, [1, 3],
-        datetime.date(1989, 1, 2),
+        u('1989-01-02'),
     ])
     def test_string_format_datetime_invalid(self, value):
         schema = Schema('string', schema_format='date-time')
@@ -604,19 +613,46 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        datetime.datetime(1989, 1, 2, 0, 0, 0),
-        datetime.datetime(2018, 1, 2, 23, 59, 59),
+        u('1989-01-02T00:00:00Z'),
+        u('2018-01-02T23:59:59Z'),
     ])
-    def test_string_format_datetime(self, value):
+    @mock.patch(
+        'openapi_core.schema.schemas._format.'
+        'DATETIME_HAS_STRICT_RFC3339', True
+    )
+    @mock.patch(
+        'openapi_core.schema.schemas._format.'
+        'DATETIME_HAS_ISODATE', False
+    )
+    def test_string_format_datetime_strict_rfc3339(self, value):
         schema = Schema('string', schema_format='date-time')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [
-        u('true'), False, 1, 3.14, [1, 3], datetime.date(1989, 1, 2),
-        datetime.datetime(1989, 1, 2, 0, 0, 0),
+        u('1989-01-02T00:00:00Z'),
+        u('2018-01-02T23:59:59Z'),
+    ])
+    @mock.patch(
+        'openapi_core.schema.schemas._format.'
+        'DATETIME_HAS_STRICT_RFC3339', False
+    )
+    @mock.patch(
+        'openapi_core.schema.schemas._format.'
+        'DATETIME_HAS_ISODATE', True
+    )
+    def test_string_format_datetime_isodate(self, value):
+        schema = Schema('string', schema_format='date-time')
+
+        result = schema.validate(value)
+
+        assert result is None
+
+    @pytest.mark.parametrize('value', [
+        u('true'), False, 1, 3.14, [1, 3], u('1989-01-02'),
+        u('1989-01-02T00:00:00Z'),
     ])
     def test_string_format_binary_invalid(self, value):
         schema = Schema('string', schema_format='binary')
@@ -632,10 +668,20 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [
-        b('tsssst'), b('dGVzdA=='),
+        b('dGVzdA=='), u('dGVzdA=='),
+    ])
+    def test_string_format_byte(self, value):
+        schema = Schema('string', schema_format='byte')
+
+        result = schema.validate(value)
+
+        assert result is None
+
+    @pytest.mark.parametrize('value', [
+        u('tsssst'), b('tsssst'), b('tesddddsdsdst'),
     ])
     def test_string_format_byte_invalid(self, value):
         schema = Schema('string', schema_format='byte')
@@ -643,16 +689,6 @@ class TestSchemaValidate(object):
         with pytest.raises(OpenAPISchemaError):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [
-        u('tsssst'), u('dGVzdA=='),
-    ])
-    def test_string_format_byte(self, value):
-        schema = Schema('string', schema_format='byte')
-
-        result = schema.validate(value)
-
-        assert result == value
-
     @pytest.mark.parametrize('value', [
         u('test'), b('stream'), datetime.date(1989, 1, 2),
         datetime.datetime(1989, 1, 2, 0, 0, 0),
@@ -664,13 +700,6 @@ class TestSchemaValidate(object):
         with pytest.raises(OpenAPISchemaError):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [u(""), ])
-    def test_string_min_length_invalid_schema(self, value):
-        schema = Schema('string', min_length=-1)
-
-        with pytest.raises(OpenAPISchemaError):
-            schema.validate(value)
-
     @pytest.mark.parametrize('value', [u(""), u("a"), u("ab")])
     def test_string_min_length_invalid(self, value):
         schema = Schema('string', min_length=3)
@@ -684,7 +713,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [u(""), ])
     def test_string_max_length_invalid_schema(self, value):
@@ -706,7 +735,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [u("foo"), u("bar")])
     def test_string_pattern_invalid(self, value):
@@ -721,7 +750,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', ['true', False, 1, 3.14, [1, 3]])
     def test_object_not_an_object(self, value):
@@ -737,20 +766,20 @@ class TestSchemaValidate(object):
         ]
         schema = Schema('object', one_of=one_of)
 
-        with pytest.raises(MultipleOneOfSchema):
+        with pytest.raises(InvalidSchemaValue):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [Model(), ])
+    @pytest.mark.parametrize('value', [{}, ])
     def test_object_defferent_type_one_of(self, value):
         one_of = [
             Schema('integer'), Schema('string'),
         ]
         schema = Schema('object', one_of=one_of)
 
-        with pytest.raises(MultipleOneOfSchema):
+        with pytest.raises(InvalidSchemaValue):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [Model(), ])
+    @pytest.mark.parametrize('value', [{}, ])
     def test_object_no_one_of(self, value):
         one_of = [
             Schema(
@@ -766,17 +795,17 @@ class TestSchemaValidate(object):
         ]
         schema = Schema('object', one_of=one_of)
 
-        with pytest.raises(NoOneOfSchema):
+        with pytest.raises(InvalidSchemaValue):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({
+        {
             'foo': u("FOO"),
-        }),
-        Model({
+        },
+        {
             'foo': u("FOO"),
             'bar': u("BAR"),
-        }),
+        },
     ])
     def test_unambiguous_one_of(self, value):
         one_of = [
@@ -800,15 +829,17 @@ class TestSchemaValidate(object):
         ]
         schema = Schema('object', one_of=one_of)
 
-        schema.validate(value)
+        result = schema.validate(value)
 
-    @pytest.mark.parametrize('value', [Model(), ])
+        assert result is None
+
+    @pytest.mark.parametrize('value', [{}, ])
     def test_object_default_property(self, value):
         schema = Schema('object', default='value1')
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [Model(), ])
     def test_object_min_properties_invalid_schema(self, value):
@@ -818,9 +849,10 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({'a': 1}),
-        Model({'a': 1, 'b': 2}),
-        Model({'a': 1, 'b': 2, 'c': 3})])
+        {'a': 1},
+        {'a': 1, 'b': 2},
+        {'a': 1, 'b': 2, 'c': 3},
+    ])
     def test_object_min_properties_invalid(self, value):
         schema = Schema(
             'object',
@@ -833,9 +865,10 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({'a': 1}),
-        Model({'a': 1, 'b': 2}),
-        Model({'a': 1, 'b': 2, 'c': 3})])
+        {'a': 1},
+        {'a': 1, 'b': 2},
+        {'a': 1, 'b': 2, 'c': 3},
+    ])
     def test_object_min_properties(self, value):
         schema = Schema(
             'object',
@@ -846,7 +879,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [Model(), ])
     def test_object_max_properties_invalid_schema(self, value):
@@ -856,9 +889,10 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({'a': 1}),
-        Model({'a': 1, 'b': 2}),
-        Model({'a': 1, 'b': 2, 'c': 3})])
+        {'a': 1},
+        {'a': 1, 'b': 2},
+        {'a': 1, 'b': 2, 'c': 3},
+    ])
     def test_object_max_properties_invalid(self, value):
         schema = Schema(
             'object',
@@ -871,9 +905,10 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({'a': 1}),
-        Model({'a': 1, 'b': 2}),
-        Model({'a': 1, 'b': 2, 'c': 3})])
+        {'a': 1},
+        {'a': 1, 'b': 2},
+        {'a': 1, 'b': 2, 'c': 3},
+    ])
     def test_object_max_properties(self, value):
         schema = Schema(
             'object',
@@ -884,38 +919,31 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
-    @pytest.mark.parametrize('value', [Model({'additional': 1}), ])
+    @pytest.mark.parametrize('value', [{'additional': 1}, ])
     def test_object_additional_propetries(self, value):
         schema = Schema('object')
 
-        schema.validate(value)
+        result = schema.validate(value)
 
-    @pytest.mark.parametrize('value', [Model({'additional': 1}), ])
+        assert result is None
+
+    @pytest.mark.parametrize('value', [{'additional': 1}, ])
     def test_object_additional_propetries_false(self, value):
         schema = Schema('object', additional_properties=False)
 
-        with pytest.raises(UndefinedSchemaProperty):
+        with pytest.raises(InvalidSchemaValue):
             schema.validate(value)
 
-    @pytest.mark.parametrize('value', [Model({'additional': 1}), ])
+    @pytest.mark.parametrize('value', [{'additional': 1}, ])
     def test_object_additional_propetries_object(self, value):
         additional_properties = Schema('integer')
         schema = Schema('object', additional_properties=additional_properties)
 
-        schema.validate(value)
+        result = schema.validate(value)
 
-    @pytest.mark.parametrize('value', [[], ])
-    def test_list_min_items_invalid_schema(self, value):
-        schema = Schema(
-            'array',
-            items=Schema('number'),
-            min_items=-1,
-        )
-
-        with pytest.raises(OpenAPISchemaError):
-            schema.validate(value)
+        assert result is None
 
     @pytest.mark.parametrize('value', [[], [1], [1, 2]])
     def test_list_min_items_invalid(self, value):
@@ -938,7 +966,7 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [[], ])
     def test_list_max_items_invalid_schema(self, value):
@@ -974,16 +1002,16 @@ class TestSchemaValidate(object):
             schema.validate(value)
 
     @pytest.mark.parametrize('value', [
-        Model({
+        {
             'someint': 123,
-        }),
-        Model({
+        },
+        {
             'somestr': u('content'),
-        }),
-        Model({
+        },
+        {
             'somestr': u('content'),
             'someint': 123,
-        }),
+        },
     ])
     def test_object_with_properties(self, value):
         schema = Schema(
@@ -996,32 +1024,28 @@ class TestSchemaValidate(object):
 
         result = schema.validate(value)
 
-        assert result == value
+        assert result is None
 
     @pytest.mark.parametrize('value', [
-        Model({
-            'somestr': Model(),
-            'someint': 123,
-        }),
-        Model({
+        {
             'somestr': {},
             'someint': 123,
-        }),
-        Model({
+        },
+        {
             'somestr': [
                 'content1', 'content2'
             ],
             'someint': 123,
-        }),
-        Model({
+        },
+        {
             'somestr': 123,
             'someint': 123,
-        }),
-        Model({
+        },
+        {
             'somestr': 'content',
             'someint': 123,
             'not_in_scheme_prop': 123,
-        }),
+        },
     ])
     def test_object_with_invalid_properties(self, value):
         schema = Schema(